Feed cover-plates for sewing machines



Sept. 19, 1967 J. a. RAKACS FEED COVER-PLATES FOR SEWING MACHINES Filed Dec. 20, 1965 I all/10111111,

INVENTOR.

Joseph G. Rokocs BY WE d -W TORNE Y United States Patent 3,342,152 FEED COVER-PLATES FOR SEWING MACHINES Joseph G. Rakacs, Cranford, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Dec. 20, 1965, Ser. No. 514,918 3 Claims. (Cl. 112260) This invention relates to devices to be applied as attachments to a sewing machine, and more particularly to improvements in feed cover-plates, i.e. work-supporting plates adapted to be applied over the work-feeding mechanism of a sewing machine so as to render the usual sewing machine work-feeding mechanism ineffective.

Feed cover-plates are useful in adapting a sewing machine for'stitching operations in which the basic workfeeding mechanism is unsuitable or not required. For example, a feed cover-plate is useful when a buttonhole attachment is secured to a sewing machine as a work-shifting mechanism built into the attachment moves the work along a selected path; when the fabric is to "be shifted manually as during embroidery work; or when a hemstitching attachment, or the like, is employed having a work feeding mechanism built into such an attachment.

An object of this invention is to provide means for improving control of thread movement during operation of a sewing machine having a feed cover-plate secured thereto.

Another object of this invention is to provide a feed cover-plate for sewing machines which will deflect thread impelled by the sewing instrumentalities away from a direction in which it might catch upon the feeding mech anisms of such sewing machines.

It is a further object of this invention to provide a feed cover-plate including means for deflecting thread impelled by the sewing instrumentalities away from the free extremities of the feeding mechanism during sewing, when the standard throat plate has been removed and a feed cover-plate is substituted therefor.

Still another object of this invention is to improve control of thread motion when a feed cover-plate is secured to a sewing machine without interfering with the feeding mechanism thereof and without requiring adjustment or modification of the feeding mechanism.

In accordance with my invention, a feed cover-plate is provided for a sewing machine having a work supporting plate and a feeding mechanism normally located substantially beneath the plane of a work supporting plate. The feed cover-plate is adapted to be substituted for the usual throat plate of the sewing machine for supporting work above the feed advancing mechanism. The feed cover-plate of the present invention includes a needle aperture and one or more thread-deflecting members extending below the feed cover-plate in overlapping relationship with one or more of the serrated bars of the feed dogs of the feeding mechanism of the sewing machine. The thread-deflecting members protect limbs of thread impelled towards the feeding mechanism during sewing by deflecting such limbs of thread away from the feed dog in order to prevent catching or snagging of those limbs of thread thereon. In this way sewing can continue without interruption such as might result from thread breakage occassioned by catching of threads on the feed dog of the feeding mechanism.

In another aspect of my invention the thread-deflecting means may be in the form of fingers extending downwardly from the lower surface of the feed cover-plate. The fingers should be designed to extend in front of the serrated or toothed bars of the feed dog or other equivalent elements of the feeding mechanism. This assures that any element of the feeding mechanism upon which thread im- 3,342,152 Patented Sept. 19, 1967 pelled by the rotary hook might be caught will be protected by the overlapping relation of the fingers with such element for all positions of the feeding mechanism during motion within its several paths or loci.

Still further, in accordance with my invention, the feed cover-plate is designed to be used with a sewing machine for a feeding mechanism, e.e. a feed dlog including a forwardly extending free extremity, such as the end of a serrated bar, in which case the fingers are positioned, shaped, and inclined downwardly and forwardly relative to the direction of rotation of the rotary hook so that the fingers extend on opposite sides of the free extremity and below it for all positions of the extremity during operation of the sewing machine.

As it is necessary that the thread deflecting means should be positioned accurately relative to the feed dog when the feed cover-plate is attached to the sewing machine; in accordance with my invention fastening members are provided on the feed cover-plate which are complemental to securing elements on the sewing machine for detachably fastening the feed cover-plate onto the work supporting surface of the sewing machine.

Further description of this invention follows with reference to the attached drawings in which:

FIG. 1 is a fragmentary front elevational view, partly in section, of a sewing machine with a buttonhole attachment secured thereto; and a feed cover-plate made in accordance with this invention is secured to the sewing machine and overlies the feed dog to render it ineffective.

FIG. 2 is a bottom perspective view of the feed coverplate shown in FIG. 1;

FIG. 3 is a fragmentary top plan view of the sewing machine bed shown in FIG. 1 with the feed cover-plate shown partially in plan and partially in phantom;

FIG. 4 is a vertical cross-sectional view taken substantially along line 4-4 in FIG. 3 with the rotary hook removed, showing the feed cover-plate and the fingers depending therefrom adjacent to one toothed bar of the feed dog. t Referring to FIG. 1 the lock stitch sewing machine shown is of well known design and it includes a worksupporting plate 16, a needle bar 11 carrying a needle 12,

a presser bar 13, and a buttonhole attachment 14 secured to the presser bar 13 by fastening means 15 and including a drive lever 16 which embraces and is oscillated by a needle clam 17 on the needle bar. The buttonhole attachment 14 also includes a work-engaging foot 20 adapted to be shifted in a buttonhole shaped path in response to motion of the drive lever 16 overated by the needle bar 11 as is well known in the art.

On the work supporting plate 10 a conventional slide plate 21 is slidably secured above a rotary hook 22 adapted for rotation counterclockwise as viewed in FIG. 3. A feed cover-plate including a body portion 23 having fingers 32 and 33 depending therefrom and tabs 35 and 36 extending from the sides thereof has been designed in accordance with this invention, and as shown in FIG. 2, has been substituted for the usual throat plate adapted to be used for sewing when the conventional feed dog 24 is employed for advancing the work. Such a throat plate is illustrated in United States Patent No. 2,862,468 of R. E. Johnson. The feed dog 24 is illustrated in plan view in FIG. 3 in which a first toothed bar 25 thereof has an extremity 26 extending in a direction to overlie the rotary hook 22. A sescond toothed bar 28 of the feed dog has an extremity 29 also overlying the rotary hook 22. The extremity 29 is integral with one end of an arcuate member 30 extending along the side of the second bar 28 away from the first toothed bar 25. The arcuate member 30 is also joined to the second bar 28 at its end opposite the extremity 29, and is employed for the purpose of as 3 suring that thread drawn by the rotary hook 22 in proximity to the second toothed bar 28 will be deflected downwardly and away from the extremity 29 of the second toothed bar 28, thereby substantially reducing the probability that a thread will be caught on the second toothed bar 28.

In the past, the extremities of feed dog bars proximate the rotary hook have been secured together by a bridge member as shown in Johnson Patent No. 2,862,468, referred to above. However, when it is desired to employ the space between the two bars 25 and 28 to provide clearance for insertion or removal of special stitching instrumentalities or other devices the bridge must be removed. For example, as disclosed in United States Patent No. 3,194,197 to Ketterer et al., a chain stitch conversion mechanism is shown which would interfere with a bar or bridge extending between the toothed bars 25 and 28. Accordingly, it is sometimes desirable or necessary to eliminate such a bridge between feed dog bars. As a result, the free extremity 26 of the first toothed bar 25 remains exposed, overhanging the rotary hook 22. A possibility exists, and actual operation has proven, that when a flat bottom feed cover-plate is used, without thread-deflecting means formed thereon, on occasion a thread drawn by the rotary hook 22 will be impelled upwardly in such a way that it will pass over the first toothed bar 25 and catch on its free end 26 thereby interfering with normal stitch formation by the sewing machine.

Accordingly, it is desired to provide means whereby this condition may be overcome. I have found that by employing a thread deflector such as a pair of fingers 32 and 33 extending downwardly from the feed cover-plate into overlapping relationship with the most forwardly extending position of the extremity 26 of the first toothed bar 25, or indeed any position of the extremity 26 thereof, that the possibility that a thread impelled at high speed will be drawn thereabout and become caught thereon is substantially eliminated.

In FIG. 1 two plies of fabric or work 34 are shown supported on the feed cover-plate body portion 23 for the purpose of formation of buttonhole thereon. The work engaging foot 20 can be caused in the usual manner to shift the work on the upper surface of the feed coverplate body portion 23 in the usual buttonhole path.

The particular form of feed cover-plate body portion 23 shown is adapted to be positively secured to the sewing '4 machine by a throat plate securing mechanism including a pair of plungers in the sewing machine which engage with tabs 35 in depressions 36 and plunger pins 51 and other mechanisms in the sewing machine described in detail in the Johnson Patent No. 2,862,468, referred to above.

Having thus set forth the nature of this invention, what is claimed herein is:

1. A feed cover-plate adapted for use on a sewing machine having an endwise reciprocatory needle, a loop-taker cooperating therewith in the formation of stitches, workfeeding mechanism including a feed-dog having at least one serrated bar formed with a free extremity, a work supporting surface, and securing means for detachably fastening said feed cover-plate to said work supporting surface, said feed cover-plate having a body portion adapted to be disposed above the level of said work supporting surface to hold the work in a position above the level of action of said feed-dog, a needle hole formed in said feed cover-plate through which said needle is adapted to reciprocate, thread deflecting means depending from the under side of said feed cover-plate and adapted to be disposed adjacent to the free extremity of said feeddog to deflect any thread limbs impelled by the action of said needle and loop-taker thereby to preclude snagging of said thread limbs on said feed-dog, and attaching means on said feed cover-plate, said attaching means being complemental to said securing means for detachably fastening said feed cover-plate to said sewing machine.

2. A feed cover-plate in accordance with claim 1 wherein said thread-deflecting means comprises fingers depending from said feed cover-plate adapted to be positioned adjacent to said feed-dog.

3. Apparatus in accordance with claim 2 wherein said fingers are spaced from each other to extend on opposite sides of said free extremity.

References Cited UNITED STATES PATENTS 937,112 10/1909 Stafford 1l2260 992,744 5/1911 Woolsey 112260 2,593,864 4/1952 Enos 112-260 JORDAN FRANKLIN, Primary Examiner.

G. KRIZMANICH, Assistant Examiner, 

